[17.0] contract: `last_date_invoiced` on `contract.line` is miscalculated except on the first line

[Jasmina-elp]

Module

contract

Describe the bug

When I create a contract with recurring_invoicing_type = 'post-paid' with multiple lines, last_date_invoiced is miscalculated except on the first line.

To Reproduce

Affected versions:

Steps to reproduce the behavior:

1. Create a contract
2. Set recurring_rule_type = 'quaterly'
3. Set recurring_invoicing_type = 'post-paid'
4. Set date_start = 2026-06-09
5. Create 3 contract.line
6. Set reccuring_next_date = 2026-06-30
7. Save the contract
8. Click on Create invoices button

Expected behavior
The last_date_invoiced on the first contrcat.line = 2026-06-29 while on the second and third is 2026-09-29.
I expected the last_date_invoiced = 2026-06-29 on the three lines.

Additional context
Linux
Python 3.12